#include <config.h>

  
  /*-------------------------------------------------------------*/
  /*--- Huffman coding low-level stuff                        ---*/
  /*---                                             huffman.c ---*/
  /*-------------------------------------------------------------*/
  
  /*--
    This file is a part of bzip2 and/or libbzip2, a program and
    library for lossless, block-sorting data compression.
  
    Copyright (C) 1996-2002 Julian R Seward.  All rights reserved.
  
    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions
    are met:
  
    1. Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.
  
    2. The origin of this software must not be misrepresented; you must
       not claim that you wrote the original software.  If you use this
       software in a product, an acknowledgment in the product
       documentation would be appreciated but is not required.
  
    3. Altered source versions must be plainly marked as such, and must
       not be misrepresented as being the original software.
  
    4. The name of the author may not be used to endorse or promote
       products derived from this software without specific prior written
       permission.
  
    THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
    OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
    ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
    DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
    DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
    GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
    WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
    NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
    Julian Seward, Cambridge, UK.
    jseward@acm.org
    bzip2/libbzip2 version 1.0 of 21 March 2000
  
    This program is based on (at least) the work of:
       Mike Burrows
       David Wheeler
       Peter Fenwick
       Alistair Moffat
       Radford Neal
       Ian H. Witten
       Robert Sedgewick
       Jon L. Bentley
  
    For more information on these sources, see the manual.
  --*/
  
  
  #include "bzlib_private.h"
  
  /*---------------------------------------------------*/
  #define WEIGHTOF(zz0)  ((zz0) & 0xffffff00)
  #define DEPTHOF(zz1)   ((zz1) & 0x000000ff)
  #define MYMAX(zz2,zz3) ((zz2) > (zz3) ? (zz2) : (zz3))
  
  #define ADDWEIGHTS(zw1,zw2)                           \
     (WEIGHTOF(zw1)+WEIGHTOF(zw2)) |                    \
     (1 + MYMAX(DEPTHOF(zw1),DEPTHOF(zw2)))
  
  #define UPHEAP(z)                                     \
  {                                                     \
     Int32 zz, tmp;                                     \
     zz = z; tmp = heap[zz];                            \
     while (weight[tmp] < weight[heap[zz >> 1]]) {      \
        heap[zz] = heap[zz >> 1];                       \
        zz >>= 1;                                       \
     }                                                  \
     heap[zz] = tmp;                                    \
  }
  
  #define DOWNHEAP(z)                                   \
  {                                                     \
     Int32 zz, yy, tmp;                                 \
     zz = z; tmp = heap[zz];                            \
     while (True) {                                     \
        yy = zz << 1;                                   \
        if (yy > nHeap) break;                          \
        if (yy < nHeap &&                               \

  	  weight[heap[yy+1]] < weight[heap[yy]])      \
  	 yy++;                                        \

        if (weight[tmp] < weight[heap[yy]]) break;      \
        heap[zz] = heap[yy];                            \
        zz = yy;                                        \
     }                                                  \
     heap[zz] = tmp;                                    \
  }
  
  
  /*---------------------------------------------------*/
  void BZ2_hbMakeCodeLengths ( UChar *len,

  			     Int32 *freq,
  			     Int32 alphaSize,
  			     Int32 maxLen )

  {
     /*--
        Nodes and heap entries run from 1.  Entry 0
        for both the heap and nodes is a sentinel.
     --*/
     Int32 nNodes, nHeap, n1, n2, i, j, k;
     Bool  tooLong;
  
     Int32 heap   [ BZ_MAX_ALPHA_SIZE + 2 ];
     Int32 weight [ BZ_MAX_ALPHA_SIZE * 2 ];
     Int32 parent [ BZ_MAX_ALPHA_SIZE * 2 ];
  
     for (i = 0; i < alphaSize; i++)
        weight[i+1] = (freq[i] == 0 ? 1 : freq[i]) << 8;
  
     while (True) {
  
        nNodes = alphaSize;
        nHeap = 0;
  
        heap[0] = 0;
        weight[0] = 0;
        parent[0] = -2;
  
        for (i = 1; i <= alphaSize; i++) {

  	 parent[i] = -1;
  	 nHeap++;
  	 heap[nHeap] = i;
  	 UPHEAP(nHeap);

        }
  
        AssertH( nHeap < (BZ_MAX_ALPHA_SIZE+2), 2001 );
  
        while (nHeap > 1) {

  	 n1 = heap[1]; heap[1] = heap[nHeap]; nHeap--; DOWNHEAP(1);
  	 n2 = heap[1]; heap[1] = heap[nHeap]; nHeap--; DOWNHEAP(1);
  	 nNodes++;
  	 parent[n1] = parent[n2] = nNodes;
  	 weight[nNodes] = ADDWEIGHTS(weight[n1], weight[n2]);
  	 parent[nNodes] = -1;
  	 nHeap++;
  	 heap[nHeap] = nNodes;
  	 UPHEAP(nHeap);

        }
  
        AssertH( nNodes < (BZ_MAX_ALPHA_SIZE * 2), 2002 );
  
        tooLong = False;
        for (i = 1; i <= alphaSize; i++) {

  	 j = 0;
  	 k = i;
  	 while (parent[k] >= 0) { k = parent[k]; j++; }
  	 len[i-1] = j;
  	 if (j > maxLen) tooLong = True;

        }
  
        if (! tooLong) break;
  
        for (i = 1; i < alphaSize; i++) {

  	 j = weight[i] >> 8;
  	 j = 1 + (j / 2);
  	 weight[i] = j << 8;

        }
     }
  }
  
  
  /*---------------------------------------------------*/
  void BZ2_hbAssignCodes ( Int32 *code,

  			 UChar *length,
  			 Int32 minLen,
  			 Int32 maxLen,
  			 Int32 alphaSize )

  {
     Int32 n, vec, i;
  
     vec = 0;
     for (n = minLen; n <= maxLen; n++) {
        for (i = 0; i < alphaSize; i++)

  	 if (length[i] == n) { code[i] = vec; vec++; };

        vec <<= 1;
     }
  }
  
  
  /*---------------------------------------------------*/
  void BZ2_hbCreateDecodeTables ( Int32 *limit,

  				Int32 *base,
  				Int32 *perm,
  				UChar *length,
  				Int32 minLen,
  				Int32 maxLen,
  				Int32 alphaSize )

  {
     Int32 pp, i, j, vec;
  
     pp = 0;
     for (i = minLen; i <= maxLen; i++)
        for (j = 0; j < alphaSize; j++)

  	 if (length[j] == i) { perm[pp] = j; pp++; };

  
     for (i = 0; i < BZ_MAX_CODE_LEN; i++) base[i] = 0;
     for (i = 0; i < alphaSize; i++) base[length[i]+1]++;
  
     for (i = 1; i < BZ_MAX_CODE_LEN; i++) base[i] += base[i-1];
  
     for (i = 0; i < BZ_MAX_CODE_LEN; i++) limit[i] = 0;
     vec = 0;
  
     for (i = minLen; i <= maxLen; i++) {
        vec += (base[i+1] - base[i]);
        limit[i] = vec-1;
        vec <<= 1;
     }
     for (i = minLen + 1; i <= maxLen; i++)
        base[i] = ((limit[i-1] + 1) << 1) - base[i];
  }
  
  
  /*-------------------------------------------------------------*/
  /*--- end                                         huffman.c ---*/
  /*-------------------------------------------------------------*/